Adeno-associated virus (AAV) vectors have the potential to replace conventional anti-retroviral therapies, or even protect against an initial HIV-1 infection. The potential of AAV vectors arises from two properties: their exceptional safety profile, and their ability to sustain very high levels of transgene expression for years. A self-complementary AAV (scAAV) vector can sustain expression of 100-200 pg/ml of protein inhibitors for more than two years. In contrast, transgene expression from a conventional, single-stranded (ssAAV) vector is more than ten-fold lower. However, scAAV transgenes are necessarily half the size of ssAAV transgenes. This limit precludes expression of full-length antibodies, and instead requires use of non-native antibody-like molecules such as single-chain immunadhesins (scFv-Fc). Moreover, the size limitation of scAAV vectors prevents inclusion of other useful molecules, for example the joining (J) chains essential for IgA multimerization, and proteins and regulatory regions useful in various